22 September 2021 Research

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Researchers investigating the effectiveness of the drug Tofersen on people with an inherited form of motor neurone disease (MND) have found it can slow progression of the disease if taken over a period of 12 months.

Results of the clinical trial, just published in the New England Journal of Medicine, indicated a notable reduction in the rate of decline in patient mobility and lung function after a year of taking the drug. The findings of the publication were discussed and explained previously in the MND Association’s research blog after their initial release at the ENCALS scientific meeting in June.

The trial investigated the effects of Tofersen in 108 people with MND known to have the faulty SOD1 gene, which is thought to account for around 2% of all cases of the disease.

In October 2021, the Phase 3 trial was extended beyond the initial six months as there were some positive indications in the data, despite the trial not meeting its primary endpoints. Trial participants continued to take the drug for a further six months and were monitored to see if taking the treatment for a longer time led to more of an effect. This was the open label phase of the trial which meant everyone took the drug, including those who were originally on the placebo (dummy drug) in the first six months.

Analysis of neurofilament levels in the blood, a potential marker of nerve cell damage and one area being investigated through MND Association funded research, showed that Tofersen reduced the amount of SOD1 and neurofilament protein levels in patients after taking the drug for six months. This suggests Tofersen successfully hits its therapeutic target and may reduce the loss of motor neurones. In addition, measurements of disease symptoms showed a slowing in the rate of disease progression at the later stages of the trial, with the group taking the drug the longest showing less decline in the outcomes that were measured.

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Dr Brian Dickie, Director of Research Development at the MND Association said: 

“These latest results provide mounting confidence that Tofersen is having both a biological and a beneficial effect in people living with SOD1 MND. They also provide important ‘proof of concept’ that similar gene therapy-based approaches may be helpful for other forms of the disease. We are closely following the recent news that Tofersen will be reviewed by the U.S. drug regulatory authorities and are in contact with the funders of the trial, Biogen, to discuss what the regulatory approval process will look like elsewhere.”

The drug has not yet been approved for use for MND anywhere in the world. It is under review by the FDA (food and drug administration) in the USA and there is an early access programme in the UK for which the approval process is undertaken by neurologists.

Professor Dame Pamela Shaw, Professor of Neurology and Director of SITraN at the University of Sheffield said:

"Patients with SOD1 mutations are relatively rare, but this trial is going to change the future of MND trials for patients. Not only can we look at other genes which also cause MND, but we now have a biomarker which we can measure to see if a treatment is working. This is going to make trials much more efficient. In future we may be able to tell in three to six months if an experimental therapy is having a positive effect.”

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